Seems this is becoming a popular way to put PPT presentations online. Here are a few applications (I'm not endorsing, just listing; haven't tried anything but Impatica.)
Wondershare PPT2Flash Professional: "PPT2Flash Professional converts PowerPoint to Flash with great accuracy through PowerPoint 2000 to 2007. With this PowerPoint to Flash conversion tool, presenters can preserve and reproduce important elements of their PowerPoint slides, such as animations, transitions, textboxes, bullets, formatting, pictures, background, sound, movie, WordArt, AutoShapes, callouts, SmartArt, and even slide master."
PresentationPro's PowerCONVERTER: "PowerCONVERTER accurately converts your PowerPoint presentation to Flash and retains all of your special effects, including: NEW Player format or Single file output; NEW Batch Mode Converts Multiple PowerPoints At Once; Narration & Continuous Audio; Inserted Video & Flash; Entrance & Exit Animations; Transitions; Hyperlinks; Auto Advance or On Click. PLUS you will have all the benefits of Flash: Easy distribution on the Web or CD-ROM; Greatly reduced file size; Stream the presentation with Audio and Video; A secure and tamper proof format; Single File output option for easy management; Viewing Capabilities with or without Player."
Impatica for PowerPoint: "...simply converts the PowerPoint file into a compressed format that is optimized for streaming over the Internet. The Impatica file is typically 95% smaller than the PowerPoint HTML files...supports most of the features of PowerPoint, including text, graphics, transitions, animation effects and, of course, narration." A reviewer says: "The good: A supremely simple packing tool for PowerPoint presentations.he bad: Too pricey for casual users."
FlashDemo's Converter: Costs a little less than most other professional converters. "Create professional-look flash presentations and e-learning courses with PowerPoint knowledge. Retain the original animations, slide transitions, timings, callouts. Preserve narration, sound, animation sound effects. Create Flash movie in extremely reduced file size. Ideal for web distribution. Compatible with PowerPoint 2007® and Windows Vista®. Extreme fast Conversion speed and easy-to-use."
Convert using Free applications: Marshall Feldman's forum post, describing a process for converting PPT to flash using a series of free applications.
OpenOffice's Impress: If you don't use a lot of fancy graphics in your ppt. presentations, here is an alternative that may work for you and it's free: Impress, like PowerPoint, will allow you to export a presentation as a single flash file that works much more smoothly than the multislide plus html file that the other programs create. [quoting Daniel Rubin's discussion posting.]
Robin Good's PowerPoint to Flash Conversion Tools - Mini-Guide, Part 1: When you get to the page, you don't immediately see the list of conversion tools or the Guide; googleAds are the biggest font. But look in the narrow grey-toned column for the Guide's Table of Contents. You can't tell by looking, but each item is a link. It's an extensive guide.
Once you have a Flash file, you have to know how to put it into a webpage. Here's one tutorial, FLASH: embedding Flash, explained, written December 31/07. "There seems to be a lot of confusion about the code needed to properly embed Flash objects within a website: it's the most frequently asked question at this site's forum. The rise of social networking sites like Myspace (who filter lots of codes) and the Eolas patent enforcement have thrown quite some confusion into the mix. In this tutorial, I'll shortly align the best options to embed Flash."